rtc: ds1347: convert to devm_rtc_allocate_device

This allows further improvement of the driver.

Link: https://lore.kernel.org/r/20191007134724.15505-6-alexandre.belloni@bootlin.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-ds1347.c

@@ -129,13 +129,13 @@ static int ds1347_probe(struct spi_device *spi)
 	data = data & 0x1B;
 	regmap_write(map, DS1347_STATUS_REG, data);
 
-	rtc = devm_rtc_device_register(&spi->dev, "ds1347",
-				&ds1347_rtc_ops, THIS_MODULE);
-
+	rtc = devm_rtc_allocate_device(&spi->dev);
 	if (IS_ERR(rtc))
 		return PTR_ERR(rtc);
 
-	return 0;
+	rtc->ops = &ds1347_rtc_ops;
+
+	return rtc_register_device(rtc);
 }
 
 static struct spi_driver ds1347_driver = {